Biomechanical Model of Outer Retinal Corrugations and Bacillary Layer Detachment in Rhegmatogenous Retinal Detachment.

Purpose: This study investigated the biomechanical mechanisms underlying outer retinal corrugation (ORC) formation in rhegmatogenous retinal detachment (RRD), focusing on the swelling dynamics of the outer retina in the presence of subretinal fluid (SRF). A mathematical framework was developed to model retinal hydration and quantify associated structural changes. Methods: The retina was modeled as a composite material in which the outer retina undergoes diffusion-driven hydration. Fluid transport was represented using diffusion equations, retinal thickness and elasticity changes were captured with the Flory-Rehner hydrogel model. The emergence of ORCs was analyzed as a mechanical instability, with an energy minimization approach applied to predict their frequency and morphology. For validation, theoretical results were compared against optical coherence tomography (OCT) imaging data. Results: The model predicts time-dependent swelling of the outer retina, accompanied by reductions in elastic modulus due to hydration. These mechanical changes promote the onset of ORCs, with their spacing and morphology determined by the balance between swelling-induced stresses and retinal stiffness. Predicted ORC patterns agree with OCT imaging, supporting the validity of the framework. Conclusions: This work provides a mechanistic understanding of RRD retinal swelling and ORC formation. By linking fluid absorption, material properties, and instability dynamics, the framework offers clinically relevant insights that may aid in assessing structural alterations and optimizing management strategies for patients with retinal detachment.